Electronica is defined as music created using electronic instruments (synthesizers, samplers, drum machines, etc) and remains dominated by that electronic sound. It can be further characterized by its emphasis on melodic and harmonic structure, and also on its catchy, danceable rhythms and bass lines. Some Electronica enthusiasts find it difficult to distinguish between what is considered Synthpop, Techno, House, Acid Jazz / Fusion, Trance, Drum and Bass, Jungle, Industrial, Dance, etc. Everyone makes their own distinctions, based on factors like: "seriousness" or "deepness" of lyrical content, presence (or lack) of lyrical content, lyrics vs. samples vs. purely instrumental, presence (or lack) of melodic content, types of sounds / timbres within the music.